How the Emotiv EPOC Works

­If you've read How Your Brain Works or have ever taken a psychology class, you probably know that your brain is home to billions of neurons, which are nerve cells. Using electrical impulses, they send messages to and through each other. Whenever your brain is working (and that means always, even during sleep), all these messages firing from neuron to neuron amount to an electrical current.

Although the brain continues to be an enigmatic subject of study, scientists have known about brain waves, which are a map of the electrical current firing from neuron to neuron, for a while. British physician Richard Caton first noticed the brain's current in 1875. By 1924, German neurologist Hans Berger found a way to read the current by developing what's known as an electroencephalograph. This kind of machine produces a graph measurement of brain waves, known as an electroencephalogram (EEG).

The system involves hooking up several pairs of electrodes on a patient's head. These electrodes are disks that conduct electrical activity, capture it from the brain and convey it out through a wire to a machine that amplifies the signal. Scientists attach electrodes in pairs on the head because they're measuring the difference in voltage between the pair. Soon after starting his research, Berger noticed that the electrical activity of brain waves correlated to a person's state of mind.

­As we mentioned, your brain fires out this electrical current even when you're sleeping. Your brain waves are usually slowest during sleep. However, slow is relative. In deep sleep, the brain transmits delta waves, which fire one to four times per second. In light sleep, theta waves fire about four to seven times per second. Alpha waves, which we emit when we're in a relaxed, conscious state, come next at about seven to 13 pulses per second. Lastly, beta waves, which reflect a very excited or stressed mind, fire fastest at 13 to 40 times per second. Your brain doesn't emit just one kind of wave at one time; rather, it emits multiple kinds of waves simultaneously. Nevertheless, one kind of wave can dominate in a given moment.

­Today, doctors are able to use EEG tests for a variety of applications, such as diagnosing epilepsy as well as other seizure disorders. The test is appropriate for diagnosing epilepsy because the everyday brain wave patterns of patients with epilepsy tend to be abnormal. EEG tests can also reveal sleep disorders, tumors and the effects of a head injury or determine whether a coma patient has become brain dead.

OK, so the medical uses of EEG are all well and good, but what does this have to do with video games and the Emotiv EPOC? Find out next.

How many brains does it take to power a light bulb?

The brain emits electrical energy -- perhaps as much as 10 watts of power -- when working at full force [source: Heemsburgen]. So, it's plausible that if enough people put their heads together and hooked themselves up, their brains could power a light bulb.